1. ELECTRONIC GUIDING CANE FINAL PRESENTATION Students : David Eyal Tayar Yosi Instructor : Miki Itzkovitz Technion – Israel Institute Of Technology Electrical Engineering Department 07/03/04

2. MOTIVATION The electronic guiding cane is designed to provide a more accurate guiding tool for the blind, than the existing laser guiding cane. The electronic guiding cane will alert its user of objects in front of him, with estimation for the distance to it. The electronic guiding cane will identify objects above the ground, that might be in the users way (should cover a little more then the users entire height ). High accuracy ( the cane should identify even the smallest objects that can interfere the user ). minimum false alarms. Low cost. 1

3. BLOCK DIAGRAM US.R US.T IR sensor BUZZER PIC 2 US.T Signal detecting circuits 40kHZ pulse transmitting circuit A/D

4. ELECTRONIC GUIDING CANE Uses Infra-Red & Ultra-Sound sensors. The microprocessor compares the measurements, and calculates the distance to the object detected. Alerts its user by vibrations, according to the distance from the object. DC consumption : 5v 120 mA. 3

5. The Infra-Red sensor Sends an Infra-Red beam. Receives the beam returned. Calculates the distance according to the angle between the beams. Outputs a DC voltage accordingly. 4

6. The Ultra-Sound measurement receiver 1 receiver 2 transmitters 5 The transmitters send a train of 40 kHz pulses. The sensors receive the returned pulses. The microprocessor checks the time delay between the pulses.

7. The Ultra-Sound measurements The Ultra-Sound transmitter send a 40 kHz pulse for 200 μsec. The microprocessor waits 1.5 msec before checking the Ultra-Sound receivers input, to avoid false identifications. The microprocessor measures the time until the pulse is returned, and calculates the distance. US transmitter US receiver 6

8. The Ultra-Sound measurement In case the object identified is not in front of the guiding cane, the microprocessor will identify it according to the time difference between the received pulses. receiver 1 receiver 2 transmitters 7

9. The Ultra-Sound measurement receiver 1 receiver 2 transmitters X the time between transmitting the pulse and receiving it is used to measure the distance from the object ( X ).

10. Y X receiver 1 receiver 2 transmitters if Y is too big, the object will not be recognized, because it is not in the users way. if Y is small, the measurement is taken into account. the time between the received pulses indicates how sided the object is ( Y ). The Ultra-Sound measurement

11. ELECTRONIC GUIDING CANE The microprocessor measures the distance using the Ultra-Sound circuit. PIC buzzer 8

12. ELECTRONIC GUIDING CANE The microprocessor measures the distance using the Infra-Red circuit. PIC buzzer

13. ELECTRONIC GUIDING CANE If no objects detected the microprocessor takes no action. Ultra SoundInfraredMicroprocessor ΦΦΦ PIC buzzer

14. ELECTRONIC GUIDING CANE If both measurements indicate an object, the minimal distance measured is the effective distance. Ultra SoundInfraredMicroprocessor 100 Cm95 Cm PIC buzzer

15. ELECTRONIC GUIDING CANE if the Ultra-Sound measurement indicates a close object (less then 20 Cm), and the Infra-Red indicates nothing, the microprocessor will ignore the measurement. Ultra SoundInfraredMicroprocessor ΦΦ 15 Cm PIC buzzer

16. ELECTRONIC GUIDING CANE PIC buzzer If the object identified by the two sensors is in the effective range, the microprocessor activates the buzzer

17. the measurements from the sensors are normalized and compared. If the measurements match, the microprocessor generates a frequency according to the shortest measurement, and activates the buzzer. ELECTRONIC GUIDING CANE 9

18. PROBLEMS & SOLUTIONS Problem : the Ultra-Sound identifies very close ( less then 15cm ) objects that are not in front of the cane. Solution : disregarding those measurements in the distance calculation algorithm. 10

19. PROBLEMS & SOLUTIONS Problem : the Infra-Red sensor identifies strong light ( pointed to the sun ) as a close object. Solution : the microprocessor identifies this case according to the Ultra-Sound measurement. If the Ultra-Sound doesn’t identify an object in the effective range, it disregards the measurement. (not implemented) 11

20. components ComponentAmountpriceTotal Price Pic microprocessor15 $ Infra Red sensor120 $ Ultra Sound sensor41 $4 $ Operative amp ps97430.94 $2.82 $ Operative amp pl08410.92 $ NPN transistor30.64 $1.92 $ Resistors & capacitors~ 800.07 $5.6 $ 20 MHz crystal11.47 $ Buzzer12.39 $ Battery114 $ Total~ 58 $

21. DEVELOPMENTS & APPLICATIONS An additional variable resistor can change the maximal distance measured. Additional switches for Disabling the IR measurements for outdoors. More accurate US sensors can improve the cane’s accuracy significantly. 12

22. Device tests Lab tests - 1.Object size ( identifies 5mm width objects ). 2.Loud noise ( the US sensors are not affected by loud or hi frequency noise ). 3.Materials ( the cane has no problem identifying any kind of materials ). Outdoor tests – 1.the IR sensor had false alarms when it was aimed towards the sun. 13

23. ELECTRONIC GUIDING CANE Electronic guiding caneLaser guiding cane gives distance estimation to close object by multilevel vibrations. One vibration level no regards to the distance. uses 2 kinds of sensors that back each other. uses only laser distance measurement. disrupted by direct sun rays. not affected by direct sun rays. low cost ( components cost ~ 58 $ ). expensive (costs ~ 1500 $ ). 14

24. ELECTRONIC GUIDING CANE High accuracy - identifies 5mm cable 1 Meter far. Multilevel vibrations - the vibrations varies according to the distance. Effective range - the cane identifies over 5 mm objects in the distances between 10 Cm & 150 Cm. Low cost – components cost - 58 $. current consumption - 120 mA. 15